Electron tube having a novel electrode support arrangement



J ly 1965 J. w. GAYLORD ETAL 3,197,655

ELECTRON TUBE HAVING A NOVEL ELECTRODE SUPPORT ARRANGEMENT Filed Oct. 9.1961 m0 4 mM M. mm M J w 5 1 MM 4 JJ W B K Z 5 ml M conductors.

United States Patent 3,197,666 ELEQTRON TUBE HAVING A NOVEL ELEC- TRODESUPPORT A'GEMENT John Wallen Gaylord and John B. Pyle, both ofLancaster,

Pa, assignors to Radio Corporation of America, a corporation of DelawareFiled Oct. 9, 1961, Ser. No. 143,846 Claims. (Cl. 313-255) Our inventionrelates to electron tube-s and particularly toa novel method ofmanufacture thereof.

One tube type has a structure comprising an envelope formed by a.stacked array of alternately disposed insulating rings usually made ofceramic, and annular lead-in Such envelope structure is characterized byseveral problems.

One problem arises as a consequence of the relatively large number ofceramic-to-metal seals required in tube structures of this type. ,In atetrode, for example, at least three insulating rings are usuallyrequired, for insulating four flange-like lead-in conductors from eachother. This involves six ceramic-to-metal seals. Such large number ofseals increases the hazard of envelope leaks.

Other problems involve the cost of tube manufacture by virtue ofcomplicated jigging techniques usually required, and the relativelylarge amount of material necessary to provide the large number ofinsulating rings and annular lead-in conductors.

Accordingly it is an object of the invention to provide an improvedelectron tube.

Another object is to provide an improved method of making an electrontube.

A further object is to provide an improved sub-assembly of electrodesand an electrode support, for ec onomical manufacture and to provide animproved structure, of an electron tube.

In one example of the invention, a sub-assembly for a tetrode type ofelectron tube includes a screen grid having an annular lead-inconductor. A tubular control grid and a cathode support are insulatinglyfixed to the screen grid lead-in conductor by means avoiding the needfor annular lead-in conductors for the control grid and cathode support.Leads for the control grid and cathode support are so oriented that notonly is it feasible to connect wire or pin-type lead-in conductors tothese leads, but a portion of the annular lead-in conductor for thescreen grid within the tube envelope is exposed for also aflixingthereto wire lead-in conductors.

In a tube structure incorporating the aforementioned sub-assembly, thewire lead-in conductors are satisfactorily insulated from each other bypassing through an insulating header in spaced relation. Consequently,the header serves the insulating function of several of the insulatingrings heretofore required.

While some support of the screen grid control grid and cathode supportis provided by the wire lead-in conductors fixed thereto asaforementioned, the major support is realized by the annular lead-inconductor of the screen grid, which is sealed through the tube envelope.

In the tube structure described, only one insulating ring is required.This ring is disposed between an anode leadin flange and the annularflange-like lead-in conductor of the screen grid. Effective insulationamong the screen grid, control grid and cathode support is afforded bythe insulating header aforementioned.

A feature of the invention involves an annular lead-in conductor for thescreen grid having a structure affording access to the control-grid andcathode-"support leads, thereby permitting a convenient fixing of theleads to their respective wire lead-in conductors.

The novel sub-assembly referred to contributes to fa- 3,197,666 PatentedJuly 27, 19x35 ice cility in manufacture, in that the major assemblingoperation may be performed by self-jigging techniques.

Further objects and advantages will become apparent from the followingdetailed consideration of an embodiment of the invention.

In the accompanying drawings,

FIG. 1 shows an elevation partlyin section of an electron tubeincorporating the invention;

FIG. 2 is sectional view, taken along the line 2-2 of FIG. '1 and showsthe electrode complement of the tube of FIG. 1;

FIG. 3 is an exploded view, partly in section, of the severalsub-assemblies constituting the tube of FIG. 1;

FIG. 4 is a bottom view of the screen grid, control grid and cathodesupport sub-assembly shown in FIG. 3;

FIG. 5 is a top view of the sub-assembly including the annular lead-inconduct-or for the screen grid,.shown in FIG. 3;

FIG. 6 is a sectional view taken along the line 66 of FIG. 3; I 7

FIG. 7 is a bottom View of the electron tube shown in FIG. 1, anddepicts the array of wire or pin lead-inconductors extending through theheader of the tube;

FIG. 8 illustrate the-relatively simple jigging required in assemblingthe parts constituting the screen grid, control grid and cathode supportsub-assembly shownin FIG. 3, and shows these parts assembled forbrazing; and

FIG. 9 shows the completed screen grid, control grid and cathode supportsub-assembly, assembled with a tubular cathode on suitable jigs in abell jar for brazing the cathode to the sub-assembly referred to.

An example of an electron tube in which the invention may be used isshown in FIG. 1. The tube includes an exposed tubular anode 10, closedat one end by a pinchedoff exhaust tubulation 12, and fixed at the otherend to an annular flange 14 which may serve as a lead-in conductor.

Coaxially within the anode 10, is a complement of electrodes, as shownmore clearly in FIG. 2, comprising (in order from outside in) a screengrid 16, a control grid 18, a tubular cathode 20 and a coiled heater 22supported on a conducting rod 24. The screen grid 16 and the controlgrid 20 may comprise tubular structure perforated by a process ofelectrical discharge machining to provide, respectively, relatively Widestiffening ribs '26, and 28 in radial register, and to form a pluralityof wires 2), 31 between the ribs, also in accurate radial register. Thecathode 2i includesa metal sleeve, made of nickel for example, andhaving thereon the usual electron emitting oxides of barium, strontiumand calcium; The heater 22 may comprise a tungsten wire having thereonan insulating coating of aluminum oxide, for example. As shown in FIG.3, one end of the heater is-fixed to the top of the conducting rod 24,the lower end portion of which is fixed at 30 to wire conductor 34 whichseal-ingly passes through a header 32 of insulating material, such asaluminum oxide. The other end of the heater is connected to a wireconductor or prong 36 also sealingly passing through the header 32.

' A feature of the invention is characterized by the fact that only oneinsulating ring 38 (FIG. 1) is utilized in the envelope structure of thetube; Consequently, the

likelihood of air leaks through the tube envelope is considerablyreduced. The ring 38, as shown in FIG. 3, is incorporated in the-anodesub-assembly 40. Also included'in this sub-assembly is a metal sealingring 42.

A further feature of theinvention concerns the header sub-assembly 44.This sub-assembly .as shown in FIG. 3 includes the header 32 and a metalsealing ring 46. The diameters of the sealing rings 42 and 46 aresuchthat sealing ring 42 fits snugly within sealing ring 46, thus renderingself-jigging of these pants feasible.

The novel screen-grid, control-grid and cathode-supanemone portsub-assembly 48 is illustrated in FIG. 3. This subassembly requires onlyone annular lead-in conductor 50, which in the assembled tube of FIG. 1,is fixed to metal ring 46 associated with the header sub-assembly 44.The annular lead-in conductor 50 is suitably fixed to or may be integralwith one end of the screen grid 16 and defines a partly closed region.The control grid 18 has one end terminating in said region and providedwith a plurality of radially extending tabs 52, 54, 56, 58, 60 shown inFIGS. 3 and 4. A ring-like cathode support 62 is provided with acylindrical flange 64 and a plurality of tabs 66, 67, 68,70 and 72.Diametrically opposed tabs 52, 54 (FIG. *3) of the control grid arecoextensive respective'ly with diametrically opposed tabs 66, 63 of thecathode support. These tabs serve to fix the control grid and thecathode support to the screen grid flange 58 in a manner to bedescribed.

Between radially extending control grid tab 52 and the radiallyextending portion of the screen grid flange 50, are disposed two pins74, 76 (only one of which, 74, is visible in FIG. 3 both being visiblein FIG. 6) made of an insulating material such as aluminum oxide, andsuitably metalized at their ends to facilitate brazing of the ends tothe inner wall of flange 350 and an upper surface (as oriented in FIG. 3or 6) of tab 52. Second group of two pins 78, 81 (FIG. 6, only pin 78being visible in FIG. 3) also made of an insulating material such asaluminum oxide. These two pins, suitably metalized at their ends, arebrazed to facing surfaces of tabs 52, 66. The tabs 52, 66 areappreciably wider than the other tabs as shown in FIG. 4, .andcoextensive in this view, to contribute ruggedness to the support of thecontrol grid 18, (FIG. 3) and cathode support 62, by the screen gridflange 50. Tab 54 on the control grid and tab 68 on the cathode supportalso serve to fix the control grid and cathode support to the screengrid flange 5,0. These tabs, however, are appreciably narrower than tabs52, 66, and are coextensive in the view of FIG. 4 and 'insulatinglyfixed to the screen grid flange 50, by an additional set of twoinsulating pins 79, 80, ('FIG. 3) also made of aluminum oxide, forexample. It has been found by applicants that this combination of tabsand pins affords a relatively rugged support of the control grid 18 andcathode support 62 on the screen grid flange 50.

The tabs extending from the control grid and cathode support, other thanthe four tabs 52, 54, 6 6, 68 refer-red I to for mounting purposes, areutilized to engage wire or rod-like lead-in conductors extending throughthe header 32. The tabs on the control grid serving this function, aretabs 56, 58, and 60, while those on the cathode support are tabs 67, 70and 72, as shown in FIG. 4,

It will be noted from FIGS. 3 and 4 that the radially extending portionof flange 50, and the tabs associated with the control grid 18 and thecathode support 62 are spaced axially of the sub-assembly 48. Thisrequires wire lead-in conductors of different length in order to engagethe differently spaced flange and tabs. To this end one group of threeangularly spaced wire lead-ins, one of which is shown at 84 in FIG. 3 isadapted to engage the tabs 67, 70 and 72 serving the cathode support,and another group of three angularly spaced wire lead-in conductors, oneof which is shown at 86, in FIG. 3, is adapted to engage the tabs 56,5,8, 60, extending from the control grid .18. Another group of threewire lead-ins one of which is shown at 87 is adapted to be fixed to theinner surface of the radially extending portion or flange 50. I

Only one lead-in conductor of each group of conductors serving theseveral tube elements is shown in FIG. 3 in the interests of simplicity.The full complement of lead-ins is shown in FIG. 7. As shown in thesefigures, lead-in conductors 84, 84a, 8411 have free ends terminating ina plane relatively close to the inner surface of header 32. The freeends of these conductors engage tabs 67, 70 and 72 of the cathodesupport 62, which is the lowermost of the elements to be engaged bylead-in conductors as shown in FIG. 3. Lead-in conductors 86, 86a, 86bhave free ends terminating in a plane farther spaced from the header 32,than the plane of conductors 84, 84a, 34b and are adapted to engage tabs56, 58 and 60 of the control grid .18. Conductors 87, 87a, 87b have freeends terminating in a plane more remote from that of conductors .86,86a, 86b, and are adapted to engage the inner surface of the radiallyextending portion of annular lead-in conductor 50 As shown in FIG. 7,each group of lead-in conductors, with the exception of headerconductors 34, 36, has the conductors therein spaced substantiallyequidistantly in a circle concentric with the header 32.. This providesa relatively rugged tripod type of support for the cathode 20 controlgrid .18 and the screen grid 16. This support for the screen gridsupplements the relatively rugged support thereof provided by theannular lead-in conductor 50.

The aforementioned engagement between the groups of lead-in conductorsrepresented by conductors 84, 86 and 87, and the tabs extending from thecontrol grid and cathode support and inner surface of flange 50, occurswhen the sub-assembly '48, after a fixing of cathode 20 thereto in amanner to be described, is positioned over the header sub-assembly 4-4with the flange 5t) telescoped over flange 88 of the sealing ring 46.The lead-in conductors or wires 84, 86 and 87 are sufficiently long tocontact their respect-ive'tabs and the flange 50, when the flange 50 istelescopingly seated on the flange 88, for self-jigging purposes.

If desired, the flange 88 may have a diameter to permit it to be'telescoped ove-r annular lead-in conductor 50. In this example, adesired position of the conductor 50 with respect to the flange 88 willoccur when the free ends of the wire lead-in conductors abutt-inglyengage their respective electrode elements, as aforementioned.Self-jigging of sub-assemblies 48 and 44, is thus feasible in either ofthe two ways discussed and contributes to facility in assembling theelectron tube shown in FIG. 1.

To assure the desired contact between the lead-inconductors 84, 86 andthe .tabs on the control grid and cathode support, the sub-assembly 48is axially rotated with respect to sub-assembly 44 after seating on theflange 88 and the positions of the tabs and the upper ends of thelead-in wires 84, 86 are observed through openings, shown in FIG. .5, inthe radially extending portion of screen grid flange 50. Six holes oropenings 90, 92, 94, 96, 98, 1% are provided in the radially extendingportion referred to. The holes are spaced from each other in an arraysimilar to the array of the lead-in tabs on the control grid and cathodesupport. It will be noted that the lead-in conductors 84, 86 are alsospaced in this array. It can readily be determined, by looking throughthe holes referred to, when a desired angular orientation of thesub-assembly 48 with respect to subassembly 44, is secured, in which theupper ends of the wire lead ius referred to engage appropriate tabs.

After such orientation and contact, relatively thin welding electrodesare extended into the holes 90 to 100, and engage and heat the tabs to asufliciently high temperature, to produce a weld between the tabs andupper ends of lead-in wires 84, 36. A welding electrode contacting theouter surface of the radially extending portion of flange 50, serves toweld the flange to the upper ends of the three lead-in wires representedby wire 87.

It is to be noted that prior to the step of welding the wires of groups84, 86, 87 to their respective lead-in tabs of the control grid, cathodesupport and flange 50, the subassembly {38 and cathode 20 (FIG. 3) havebeen assembled and fixed. The assembling operation to providesub-assembly 48 involves first mounting the screen grid, control gridand cathode support on a mandrel 102, in a position inverted from thatshown in FIG. 8. In such inverted position of the mandrel 102, it willbe convenient to mount thereon first the cathode support 62 shown inFIG. 3. Thereafter the three insulating pins 78, 81, 80 (FIGS. 3 and 6)are placed on the tabs 66, 68. The control grid is positioned so thatits tabs 52, 54 engage the previously positioned insulating pins 78, 8G,81. Thereafter the three insulating pins 74, 76, 79 are placed on thecontrol grid tabs 52,54 The flange 50 of the screen grid 16 is thentelescoped over the elements so rfar mounted while angularly orientingthe same so that the lead-in tabs 56, 58, 60, 67, 78 and 72 are visiblyoriented through holes 98 to over the ends of the wire condoctors asshown in FIG. 5. It should be noted that when mounting the cathodesupport 62 and the control grid 18 on the mandrel 102, these parts areangularly oriented so that tabs 52, 54 of the control grid are incoextensive register with the tabs 66, 68 "on the cathode support 62.When this register occurs, the lead-in tabs 56, 58, 68, 67, 78 and 72automatically assume the orientation depicted in FIG. 4.

It will be seen in FIG. 8, that the control grid 18 and screen grid 16have openings 184, 106 at the ends thereof remote from flange 58 andtabs 52, 54. The mandrel 102 includes a pin-like portion 107 adapted toenter the afore mentioned openings, snugly. The mandrel also includestwo progressively wider portions 108, 110, adapted to snugly engage theinner surface of control grid 18 and the cylindrical portion of flange50, respectively. The portion 188 is also adapted to engage snugly theinner wall of cathode support 62.

The mandrel 102 may be positioned in an oven 112 either in the positionshown. in FIG. 8 or in the inverted position assumed during the mountingof the parts thereon. The oven contains a reducing gas such as hydrogenand is heated to a temperature of about 800 C. for brazing the ends ofthe insulating pins to their engaged tabs and to the inner surface offlange 58. To permit such brazing the ends of the pins are coated with ametal such as molybdenum.

After the sub-assembly 48 has been completed in the manner described andbefore this sub-assembly ,is mounted on the header sub-assembly 44, thecathode 28, is mounted on and fixed to the cathode support 62. Thecathode is provided with a structure to facilitate its mounting onsupport 62. Thus, one end portion 114 of the cathode is appreciably oflarger diameter than the other portions 116, 118 thereof. The outerdiameter of portion 114 is such as to afford a snug fit into thecylindrical portion 64 of the cathode support. The

diameters of the cylindrical portion 64 of the cathode support 62 andthe control grid 18 are substantially the same so that in addition tofacilitating jigging, a convenient reference means comprising thedifference between the outer diameters of portions 114 and 118 of thecathode is provided to determine the spacing between the cathode and thecontrol grid. The wall of portion 116 of the cathode is relatively thinfor service as a heat dam.

In assembling the cathode 20 in the subassembly 48, two jigs 122, 124(FIG. 9) are employed. Jig 122 comprises a cylindrical portion adaptedto enter the cathode 20 snugly and to abut against the lower end wall ofthe cathode as viewed in FIG. 9. Jig 124 includes a relatively thickportion 126 adapted to enter holes 184, 186, in the end walls of controlgrid 18 and screen grid 16, respectively, of sub-assembly 48. Jig 124also includes a relatively thin portion 128 adapted to enter arelattively small hole 130 in the end wall of the cathode 28. When thejig portion 18 is extended into the hole 130 and the cathode extendedthrough the cathode support 62 so that the support engages therelatively thick cathode portion 114, the cathode and sub-assembly 48are in correct relative positions for fixing the cathode to its support62.

Such fixing may be effected by disposing the cathode 20 and sub-assembly48 assembled as aforementioned, in a bell jar 132 containing a reducinggas such as hydrogen. A coil 134 is then positioned around the flange 64of the cathode support and connected by leads 136, 138, to a suitablesource of RF. power for heating the support flange 64 and the relativelythick portion 114 of the cathode to a brazing temperature. In view ofthe relatively large magnitude of power required to energize the coil134, the coil and its leads 136, 138 may be tubular to accommodate acooling fluid circulated therethrough.

After the cathode 28 has been added to sub-assembly 48 in the mannerindicated, sub-assembly 48 may be mounted on the header sub-assembly 44with the cylindrical portion of the screen grid flange 58 telescopedlover or within the cylindrical portion 88 of flange 46, and weldedthereto. It is to be noted that when the flange 58 is seated intelescoped relation over flange 88, or when the flange 50 is disposedwithin flange 88 and the lead-in conductors 84, 86, 87 serve as topmeans, the elements of subassembly 48 are in accurate coaxial relationwith respect to the elements of the header sub-assembly 44, andappropriately axially spaced.

Thereafter, the anode sub-assembly 48 in mounted on the headersub-assembly 44 with the sealing flange 42 on the former snugly receivedwithin the sealing flange 46 of the header. When seated relation offlange 42 in flange 46 occurs, the anode sub-assembly is coaxial withthe combined assemblies 48, 44, and the assemblies are desirably spacedaxially.

The extensive self-jigging that is thus feasible contributes to economyin manufacture as well as to an improved tube structure.

It will be noted that in the complete tube, cylindrical flanges 42 and46 constitute an annular lead-in conductor serving the screen grid 16.While the screen grid is also served by wire lead-ins, as explained inthe foregoing, the added provision of an annular lead-in conductor is ofadvantage not only in affording self-jigging and support for the controlgrid and cathode, but in widening the utility of the tube. Thus itsoutput electrodes, (the anode and screen grid) may be associated at willwith either lumped or tank cicruits. The flange lead-in conductor forthe screen grid, moreover, serves advantageously as a heat dissipatingmeans, thereby contributing to a reduction in the operating temperatureof the screen grid and to improved tube operation.

A feature of particular significance in the manufacture of the tubeinvolves the order in which the ribs 26, 28 and the Wires therebetweenin the control grid 18 and screen grid 16, are formed in relation toassembling of the parts constituting sub-assembly 48. In thisconnection, it should be noted that the ribs and grid Wires in the'twogrids should be accurately aligned radially of the grid structures. Itis diflicult to secure such alignment during the step of assembling theparts of this sub-assembly. Therefore, in accordance with the invention,the parts forming sub-assembly 48 are first assembled and the controlgrid 18 and the cathode support 62 are angularly oriented to dispose thetabs 56, 58, 68, 66, 67, 68, 70, 72, in the pattern shown in FIG. 4.After such assembling step and a fixing of the parts in their assembledpositions,

the two grids are subjected to an operation of forming the ribs 26, 28and the grid wires therebetween. This operation may involve electricaldischarge machining utilizing a breach electrode of a shape to formaccurately radially aligned axial slots in the'two grids between desiredaccurately radially aligned bars and wires as described in Patent2,980,984. It is thus apparent that the step of angularly orienting thecontrol grid and the screen grid to form the tab pattern shown in FIG. 4is not critical and is satisfactory if the mounting tabs 52, 54,-and 66,68 are approximately in coextensive relation to accommodate theinsulating pins aforementioned therehetween. The angular spacing betweenthe other tabs employed as con- 3,197,eee

doctors, is sufficiently large to permit of some variation thereinwithout harmful results.

It is apparent from the foregoing that we have provided an improvedelectron tube structure and a novel and advantageous method of makingthe same.

We claim:

1. An electron tube having an envelope, a first elongated electrodewithin said envelope, an annular conductive structure connected to oneend of said electrode and sealed through the wall of said envelope, saidstructure defining a cup-shaped portion within said envelope, and asecond electrode insulatingly fixed to spaced portions only, of saidannular structure and within said cup-shaped portion.

2. An electron tube having an envelope an elongated screen grid withinsaid envelope, an annular flange extending through the wall of saidenvelope and conductive- 1y engaging one end of said screen grid, and acontrol grid in coaxial relation with respect to said screen grid, saidcontrol grid being insulatingly fixed to one face only, of said flangeand extending beyond the opposite face of the flange.

3. An electron tube having an envelope, an annular metallic memberextending through the wall of said envelope and including a portionextending inwardly of said envelope, and an electrode sub-assemblywithin said envelope, said electrode sub-assembly comprising a pluralityof electrodes, and a metallic support for one of said electrodes. fixedto said inwardly extending portion, the other electrodes beinginsulatingly supported on said support.

4. An electron tube having an envelope, a conductive electrode supportextending through the Wall of said envelope and having a fiat surfaceportion, and a plurality of electrodes supported on said flat surfaceportion only, in insula'tedrelation with respect to each other and saidsurface portion.

5. An electron tube having an envelope, a conductive annular electrodesupport extending through the Wall of said envelope, said supportincluding a cylindrical flange entirely within said envelope anddefining a partly closed space, a first electrode conductively mountedon said support at a region thereof outside of said space, and a secondelectrode insulatingly mounted on said support and within said space.

6. An electron tube comprising an envelope, a plurality of electrodeswithin said envelope, an insulating header, a plurality of lead-inconductors extending through said header and electrically connected tosaid electrodes, and an annular metallic support conductively engagingone of said electrodes and extending through a wallof said envelope, theother electrodes being insulatingly en gaging on said support withinsaid envelope.

7. An electron tube having an envelope, an annular conductive supportstructure extending through a Wall .of said envelope, a first electrodeconductively fixed to said structure, a second electrode having a firstgroup of radially extending tabs insulatingly fixed to said structureand a second group of radially extending tabs angularly spaced from saidfirst group, and a plurality of wirelike conductors connected -to saidtabs of said second group.

8. An electrode mount comprising a first tubular electrode, an electrodesupport having a tubular portion coaxial with said first electrode, saidfirst electrode and said tubular portion having substantially the sameinner diameter, a second tubular electrode having an end portion thereoffixed to the inner surface of said tubular portion, and another portionextending within said first electrode, the wall of said second electrodeat said end portion being thicker than the wall of said another portionto provide a desired spacing between said another portion and said firstelectrode, a common conducting support for said first electrode and saidelectrode support,

and means electrically insulating said second electrode from said commonsupport.

9. An electron tube comprising an envelope, a header forming a wallportion of said envelope, a metallic flange coaxial with said header andsealed through another wall portion of said envelope, an electrodesupported on said flange, said flange having a radially extendingportion normal to the axes of said header and flange, and a lead-inconductor extending through said header along an axis normal to and inregister with said radially extending portion, whereby said conductor isadapted to be fixed to said radially extending portion.

10. An electron tube comprising an envelope, a metal support within saidenvelope and extending through a wall thereof, a first tubular electrodewithin said envelope and conductively supported on said metal support, asecond tubular electrode within said first electrode and having an endportion adjacent to but spaced from said metal support in a directionaway from said first electrode, a third tubular electrode within saidsecond electrode and having an end portion adjacent to but spaced fromsaid first named end portion in said direction, said end portions eachhaving a plurality of conductive tabs extending radially therefrom, twoof said tabs on each of said second and third electrodes being in facingrelation, the others of said tabs being oifset angularly, and aplurality of leadin conductors extending in a direction normal to saidtabs and fixed thereto.

11. An electron tube having an envelope, a header in the wall of saidenvelope, an annular metallic structure in coaxial relation to saidheader and extending through the wall of said envelope, a firstelectrode conductively supported on said annular structure, a secondelectrode extending through said annular structure and having an endportion adjacent thereto, a plurality of angularly spaced tabs extendingradially from said end portion, insulating =means fixing two of saidtabs to said structure, others of said tabs being free from contact withsaid structure, a first group of wire-like lead-in conductors extendingthrough said header and fixed to said others of said tabs, and a secondgroup of wire-like lead-in conductors extending through said header andbetween said others of said tabs into contact with said annularstructure.

12. An electron tube comprising an envelope, an annular metallic supportstructure sealed through an annular portion of said envelope, a firsttubular electrode fixed at one end thereof to said structure, a secondtubular electrode extending into said first electrode and having an endportion extending beyond said first electrode and adjacent to saidstructure, two tabs extending in a radial array from said end portionand substantially oppositely disposed in said array, one of said tabshaving an appreciably greater arcuate extent in said array than theother tab, an insulating pin sealed to one face of said other tab and tosaid structure, and two spaced insulating pins sealed to one face ofsaid one'of said tabs and to said structure, whereby said secondelectrode is ruggedly supported on said structure.

13. An electron tube having an elongated envelope closed at one end byan anode and at the other by an insulating header, said envelopeincluding an insulating sleeve intermediate said anode and header, afirst annular metal flange connected to said anode and sealed to one endof said sleeve, a second annular metal flange sealed to said header andto the other end of said sleeve, an electrode within said envelopemounted in conductive relation on said second metal flange, a pluralityof electrodes mounted in insulating relation on said second metalflange,

and a plurality of lead-in conductors extending through said header andin contact relation with said plurality of electrodes.

14. An electron tube having an envelope comprising an insulating sleeve,a tubular anode structure supported on one end of said sleeve, and anelectrode mount supported 9 on the other end of said sleeve, said mountincluding a metal flange and an insulating header, said metal flangebeing sealed between said other end of said sleeve and said header, saidmetal flange including a portion extending within said envelope, aplurality of electrodes insulatingly mounted on said portion, and aplurality of lead-in conductors extending through said header andelectrically connected to said electrodes.

15. An electron tube comprising an envelope, an electrode assemblywithin said envelope, said assembly including a plurality of electrodesand comprising an annular conductor extending through the wall of saidenvelope and conductively supporting one of said electrodes, saidconductor having a planar surface, and

means within said envelope insulatingly supporting the others of saidelectrodes on said planar surface.

Reierences Cited by the Examiner UNITED STATES PATENTS 2,428,661 10/47Fitzmorris 313-265 X 2,469,331 5/49 Eitel etral 313-247 X 2,527,12710/50 Gormley et a1 313-265 X 2,808,528 10/57 Martin 3133 17 X 2,916,64912/59 Levin 3l3-257 X 2,935,783 5/60 McCullough et al 2925.16 2,996,6378/61 Garner et a1. 313--265 3,068,548 12/62 Hergenrother et a1. 2925.16

GEORGE N. WESTBY, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,197,666 July 27, 1965 John Wallen Gaylord et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below Column 3, line 25, for "Second" read A second column 5,lines 68 and 69, for "relattively" read relatively line 70, for "18"read 128 column 6, line 24, for

"in" read is column 7, line 53, strike out "on".

Signed and sealed this 19th day of April 1966.

TEAL) ttest:

RNEST W. SWIDER nesting Officer Commissioner of Patents EDWARD J.BRENNER 7

1. AN ELECTRON TUBE HAVING AN ENVELOPE, A FIRST ELONGATED ELECTRODEWITHIN SAID ENVELOPE, AN ANNULAR CONDUCTIVE STRUCTURE CONNECTED TO ONEEND OF SAID ELECTRODE AND SEALED THROUGH THE WALL OF SAID ENVELOPE, SAIDSTRUCTURE DEFINING A CUP-SHAPED PORTION WITHIN SAID ENVELOPE, AND ASECOND ELECTRODE INSULATINGLY FIXED TO SPACED PORTIONS ONLY, OF SAIDANNULAR STRUCTURE AND WITHIN SAID CUP-SHAPED PORTION.